1. Field of the Invention
This invention relates to a large-capacity information storage apparatus which has removable storage media, such as optical discs, assembled for use and to an information processing method.
2. Description of the Related Art
Recently, the amount of data managed in offices has become enormous. To manage those large amounts of data, an autochanger is proposed in Unexamined Japanese Patent Application Publication No. 4-301282. The autochanger can hold a plurality of optical discs (e.g., rewritable opto-magnetic discs or CD-ROMs) serving as removable large-capacity information storage media. An autochanger also enables selective access, and has a control section which receives access from a workstation and reads data from a specified optical disc. The control section has the function of reading other data designated in other access information from the workstation into memory in advance, while the workstation is processing the read-out data. Because accessing the memory is done faster than access to the optical disc, use of a pre-reading function shortens the access time on the whole.
The transporting and loading of an optical disc to the optical disc drive and the removing of an optical disc from the disc drive, however, takes a very long time as compared with the data processing in the workstation or memory.
The pre-reading of the memory reading data can shorten the access time for reading data to some extent. In writing data, however, when the data processed at the workstation is to be written to an optical disc, the corresponding optical disk is going to be accessed.
To access an optical disc, a check is made to see whether or not the optical disc is loaded in an optical disc drive. If it is loaded, then the optical disc drive is accessed. If it is not loaded, the optical disk loaded in the optical disc drive is removed and returned to a storage cell. Then, the optical disc containing the data to be accessed is taken out of a storage cell and loaded in the optical disc drive. Thereafter, the optical disc drive is accessed.
The time required for the process is approximately ten seconds in the case of ordinary 5-inch optical disc drives, several hundred or several thousand times the processing time needed for accessing the memory. The main causes are the spin down process (the process of stopping the rotating motor in the optical disc drive) performed before the optical disc is removed from the optical disc drive, and the spin up process (the process of bringing the rotating motor to a specific number of revolutions in the optical disc drive) after the loading of the disc.
In the future, the amount of data managed in offices is expected to increase rapidly as a result of a wide spread use of multimedia data, such as moving picture data. In such a situation, the number of direct accesses to optical discs is considered to increase.